Well Turbo,
There are a few things I look at.
Usually when a port is blocked its blocked. Meaning that no files will ever transfer. When a file starts uploading fast like normal and then slowly drops off to nothing I think of two things.
The Macrovision aka RIAA/MPAA have files that are able to download, some at rapid speeds then turn out to be fakes and the high speeds are to crash your connection. They stay steady, or the ones that you might find that will start ok, then slow down to nothing and stop.
Now that is alot like the throttling however, this is something you might find one in a hundred files that this will happen with.
So basically its only once in a while.
The one that says 'Its Your ISP' to me is when you see this on a regular basis.
There is a way to test it, it would involve having a dialup modem installed on your computer.. easy really to get a cheap one and plug it in if you dont have one.
Juno has a offer for 10 hours free a month, you sign up and hook up the dial - up connection and try mx, if it works you know 100% its your ISP.
http://account.juno.com/s/landing?action=viewProduct&productId=free&group=freeHope this helps you some, I have been dealing with several Rogers customers lately. I dont like what they are doing and if we can help in anyway please dont hesitate to ask us..